Interlocking safety switch system



Feb. 19, 1952 w. A. RAY

INTERLOCKING SAFETY SWITCH SYSTEM Original Filed Nov. 13, I944 kMxEQ wasPatented Feb. 19, 1952 INTERLOCKING SAFETY SWITCH SYSTEM William AltonBay, North Hollywood, -Calif., as-

signor to General Controls 00., a corporation Original applicationNovember 13, 1944, Serial No. 563,166. Divided and this applicationJanuary 10, 1948, Serial No. 1,526

2 Claims. 1

This invention relates to the control of burners, such as in domesticgas ranges, and particularly to the control of the oven or broilerburners.

This application is a division of an application filed May 13, 1944, inthe name of William A. Ray, now Patent No. 2,446,718, and entitled FuelIgniting System.

It is an object of this invention to provide a safety switch system,especially in connection with fluid fuel burners. It is thereby assuredthat the burners may be safely operated without danger of explosions dueto an undesired accumulated fuel.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of oneembodiment of the invention. For this purpose there is shown a form inthe drawings accompanying and forming part of the present specification.This form will now be described in detail, illustrating the generalprinciples of the invention; but it is to be understood that thisdetailed description is not to be taken in a limiting sense, since thescope of this invention is best defined by the appended claims.

In the drawings:

Figure 1 is a schematic showing of a system incorporating the invention,and

Fig. 2 is a view showing a different operating position of one of thevalves employed in the system illustrated in Fig. 1.

The system of the invention contemplates the use of a photo-emissiveelectronic device which is energized by a suitable source, and operatedto supply current for the system by the light of the pilot flame. Theresponse of such a device is substantially instantaneous. Thus, it isproposed to energize the device to actuate an igniter, and to open thevalve controlling the pilot burner, as by pressing a push button.Release of the push button serves to open the control valve for the mainburner, but only if the pilot flame is burning. If the pilot flame isnot burning, such release will not open the control valve and, further,will cause return of the pilot valve to closed position. Thus, the needof a constantly burning pilot flame is obviated. Further, by lightingthe pilot burner first and causing the control valve for the main burnerto open only if the pilot flame is burning, escape of any considerableamount of unignited fuel, such as might occur if it were attempted tolight themain burner directly, is prevented.

The system may be utilized for the control of fuels generally, eithergaseous or liquid. As

shown, it is particularly adapted for controlling a main burner I whichmay be used, for example, to heat the oven or for broiling in aconventional cooking stove which utilizes gaseous fuel. The main burnerI is adapted to be supplied with fuel from an appropriate source bymeans of a pipe 2, the flow of. fuel to the burner being controlled by amain or control valve 3. A pilot burner 4 provides a flame 5 forlighting the burner I when valve 3 is opened, and is supplied with fuelby a conduit 6 connected to pipe 2 between the control valve 3 and thesource of fuel supply. In this way, the supply of fuel to the pilotburner is not affected by closing of the control valve 3. A pilot burnervalve I is interposed in the conduit 6 for controlling the supply offuel to the pilot burner 4.

The arrangement is such that the pilot flame does not burn continuously,but is extinguished when the main burner is extinguished, and lightedonly when the main burner is to be lighted. Further, unless the pilotflame is burning, the control valve 3 cannot be opened; and, should thepilot flame 5 fail at any time, the control valve 3 will immediatelyclose.

The control circuit includes a light sensitive device 8, such as aphoto-tube, that responds to the light produced by the pilot flame 5,appropriate shields (not shown) being provided to exclude light from anyother source. Thus, although the main burner I, the pilot burner 4, andthe light sensitive device 8 are shown for illustrative purposes aslying in the plane of the drawing, it is preferred that the device 8 andthe pilot burner 4 lie in a plane normal to the plane of burner 4 andthe main burner I. In'this way, the light sensitive device 8 is notexposed to the light of the main burner flame. A focusing device 9 maybe used to project light from the flame 5 into the light sensitiveelectrode of the tube 8.

The control valve 3 is shown diagrammatically and is of a novel type,being adapted when open to supply either a large quantity of fuel (highfire) or a small quantity (low fire) to the main burner I in accordancewith the amount of heat required from the burner I. Such a valve isdisclosed and claimed in a co-pending application filed in the name ofWilliam A. Ray on October 28, 1944, under Serial No. 560,793, now PatentNo. 2,526,972, and entitled Fluid Control System.

The valve 3 is shown as having a body Ill with an inlet chamber IIandran outlet chamber I2 separated by a wall I3. Thechambers II and I2are adapted to be in communication by a port It extending through thewall l3 and defined by a vertically extending tube l providing valveseats l5 and H at its upper and lower ends respectively. A valve memberI8 is provided for controllin the port i4 and includes closure members29 and 2E, secured together in spaced relationship by a stem 22, whichcooperate respectively with seats i3 and H to close the port l4. Whenthe valve member! is in its lowest position, the closure 25 is on itscooperating valve seat closing the port l4 and preventing anycommunication between the chambers H and I2. This is of course theclosed position of the valve 3, and is indicated by broken lines inFig. 1. When the valve member i8 is in its upper position, closuremember 2| is on its cooperating valve seat 11, also closing port i4 butcommunication between chambers H and i2 is maintained by a reduced port23 between port l4 and the outlet chamber l2. This is the low fireposition of the valve and is shown in Fig. 1. With the valve member I3is an intermediate position both closure members and 2| are sufficientlyspaced from their respective seats I5 and I1 to allow free communicationbetween the chambers H and |2 via port i4. This is the high fireposition of the valve and is shown in Fig. 2.

Means are provided whereby the valve 3 is caused to open and to close inaccordance with energization or de-energization of a controllingcircuit. Further means are provided by which valve 3 assumes the lowfire or high fire position in accordance with the heat requirements ofthe system. Thus the upper wall of the inlet chamber II is formed by aflexible diaphragm 24 to which is secured the valve member l8. A similardiaphragm is secured in body I0 above the diaphragm 24 and cooperateswith the body In and the diaphragm 2 to form a pressure chamber 26. Thediaphragm 25 forms the lower wall of a working chamber 21 in the bodyIt].

The diaphragms 24 and 25 are maintained in spaced relation by a memberfixed on the under side of diaphragm 25 in axial alinement with thevalve member l8 and having a projection 3| adapted to engage the top ofdiaphragm 24. The member 30 also has an extension 32 projecting upwardlythrough the diaphragm 25 and forming a clevis to which is pivoted oneend of a link 33. The other end of the link 33 is pivoted to a dependingarm 34 of the operating lever 35, pivotally supported at 36 in the bodyI9, and urged downwardly about its pivot 36 by a compression spring 31.

A charged Sylphon or expansible chamber 38 supported in body l9 servesby engagement with arm 34 to determine the position of lever about itspivot. The Sylphon 38 forms one element of a conventional pressureresponsive system 39 and for this purpose is connected by means ofcapillary tube 40 with a ieeler bulb 4| in thermal relation with thespace or object arranged to be heated by fuel passed by the valve 3 andthe temperature of which it is desired to control. A second expansiblechamber or Sylphon 42 is also connected to the capillary tube 40 andisadjusted to a desired volume by an adjusting knob 43. By adjustment ofthe volume of chamber 42, the position of lever 35 for any giventemperature at the feeler bulb 4| may be altered. The knob 43 may beprovided with an appropriate scale to assist. in such adjustment, andmay be marked in temperature degrees. A stop pin 44 serves to limitmovement of lever 35 in response to a lowered temperature, that causesSylphon 38 to contract and pull lever 35 downwardly.

An operating or pilot valve 46 is provided for controlling the pressuresin chambers 26 and 21 and causing the valve 3 to open and to close.Valve 45 includes a fluidtight casing 41 in continuous communicationwith pressure chamber 23 as by a conduit 43. Casing 41 is arranged to bevented to the atmosphere Or provided with fluid under pressure from thepipe 2 by a pair of spaced oppositely directed nozzles 49 and 50. Nozzle49 communicates with the exterior of casing 41 as by a vent tube 5|,while the nozzle 59 communicates with the pipe 2 by tube 52.

A member 53 is pivotally supported at 54 in casing 41 for angular motionbetween the nozzles 49 and 50, being biased as by a tension spring 55 toa position in which it closes the vent nozzle 49 and opens the inletnozzle 50. An electromagnet 56 is provided to act on member 53 inopposition to the spring 55. For this purpose, member 53 is a magneticarmature. Thus upon energization, magnet 56 swings member 53 to aposition in which the vent nozzle 5| is open and inlet nozzle 59 isclosed. The working chamber 21 is under fluid pressure at all timesthrough the connection 51 to the tube 52.

The operation of the control valve 3 may now be set forth. The positionof diaphragm 25 is determined by lever 35 in accordance with thetemperature requirements of the system independently of pressureconditions in the valve 3. With magnet 55 tie-energized, vent 49 isclosed and fluid pressure from the pipe 2 is present in casing 41 andpressure chamber 23, where it serves to maintain diaphragm 24 in itslower position with closure 29 of valve member l8 on seat H], thuspreventing passage of fuel through valve 3. Upon energization of magnet56, member 53 swings to vent casing 41 and chamber 26 to the atmosphere,so that the pressure of the fuel below diaphragm 24 urges the diaphragmand valve member I3 upwardly until stopped by engaging the projection 3|carried by diaphragm 25. If the temperature requirements of the systemare such that a low fire is all that is required, lever 35 will be sopositioned that projections 3| does not engage the diaphragm 24, hencethe diaphragm and valve member I8 can move to their upper positionallowing member 2| to seat. Thus fuel is supplied to burner I only bythe reduced port 23, as shown in Fig. 1. If, however, a high fire isrequired, lever 35 will be so positioned that projection 3| stopsdiaphragm- 24 and valve member I8 at an intermediate position in whichboth closures 2G and 2| are unseated, giving a full valve opening. Upondeenergization of magnet 59, pressure will be reestablished in chamber25. Pressures on opposite sides of diaphragm 24 are thus equalized andthe diaphragm 24 is moved downwardly by the weight of valve member I8 tocause closure 29 to seat and prevent passage of fuel to the burner Thetransition of the valve member l8 from high fire to low fire position,or vice versa can, of course, occur at any time while the valve is openand the main burner in operation.

The main burner is arranged to be lighted by the actuation of a switchmechanism 50 and through the intermediary of a pilot burner. Thus, whenthe push button is pressed, the pilot burner is lighted. When the pushbutton is released, if the pilot burner is burning, the control valve 3will be opened. If the pilot burner has failed to light, the controlvalve 3 will remain closed and the pilot burner valve will close.

The pilot burner valve l comprises a spring pressed closure memberhaving a projection or stem 5i which when pressed opens the valve. Abell crank 52 pivoted at $3 serves by clockwise movement about its pivotto open the valve 7. The upper end of bell crank 62 carries a roller {55which engages the face of a magnetic armature 6B. The armature isadapted to be moved to and from engagement with the polar faces of anelectromagnet (3'5. When armature 56 is in engagement with the magnet E?as shown, or in attracted position, valve "1 will be open. If no forceis present to maintain armature 355 in this position, armature and arm62 will be returned to the broken line position and valve i will close,in response to force exerted by the spring in the valve, supplementeddesired a tension spring 63.

The armature has a push rod 55. with a con vex outer end adapted to beengaged by the inner end of a push button or actuating member H. A li htcompression spring '52 is confined between flanges "l3 and i lrespectively on pus rod 551 and push button 3! for urging the push rodand the push button axially apart. However, it is to be understood thatspring l2 does not sufficient strength to move rod til and 65 towardmagnet 61 in opposition to the exerted by spring Spring it is merely forthe purpose of returning the push button "it to initial position whenreleased, ii the arma' e is retained in its attracted position by magnet5?.

A switch arm '5? is attached to push rod cc carries a contact 78 adaptedto engage a stationary contact is when armature 56 is in eng ment withmagnet 9?. A similar switch arm carrying a contact ill is arranged to bemoved to engage a stationary contact 82 when push button I! is depressedto move armature ES to the magnet Contacts 8| and iii are separated uponreturn of push button ii to its initial position. Similarly contacts illand '39 separate upon movement of armature out of engagement with magnet62. Another arm 83 carries a contact which engages a fixed contact 95when the push button ii is in its initial or normal position, contacts84 and 85 separating when push button ii is depressed. The operation ofthe push button mechanism will be explained after a discussion of thecontrol circuit.

The control circuit includes the phototube 8 which is energized by analternating current source and is operative to supply current to thecircuit only as long as the pilot flame 5 is burning. The phototube 8serves, in addition, as an electronic emission rectifier for supplyingunidirectional current to the electromagnet 5? for maintaining the pilotburner valve l open and to magnet 55 which serves to open and maintainopen the control valve 3. If the pilot flame is not burning, no currentis delivered by the phototube 8 and valves 3 and 1 are not maintainedopen. Accordingly the phototube ii performs a plurality of functions: itnot only serves as a control device, but also provides rectified currentfor the system.

The phototube 8 preferably supplies suiiicient current for theelectromagnets 55 and 5'! without the use of an amplifier. Accordingly,the tube 8 is shown as of the electron multiplier type, for example ofthe type known as S3l-A. Such a tube includes a photo-sensitive cathode83 which emits electrons when its active surface is til illuminated, asby the flame 5. The anode 89 finally receives the electrons produced inthe tube by successive action of the electrons upon a number of dynodesor secondary emitters 9!}, 9|, 92, 83, 94, 85, 96, 91 and 98, nine beingshown in the present instance. In order that these electrodes serveeffectively to reinforce, by secondary emission, the original electronicstream emanating from the cathode 88, they are connected to taps on thesecondary winding 99 of a step up transformer 190. The primary winding19! is adapted to be connected to a commercial source of alternatingcurrent by leads H12 and IE3.

The operation of a tube of this character is well known. A relativelyweak stream of electrons is dislodged from the photo-sensitive surfaceof the cathode 88, which stream is greatly reinforced by secondaryemission successively from the auxiliary electrodes 92 and 98 inclusive,which are successively encountered by the elecron stream. The outputcurrent between the anode 89 and the last dynode 98 is unidirectional,and the maximum of which the device is capable.

Accordingly, the coil of the electromagnet 56 of valve 46 is connectedbetween anode 89 and dynode 9i, since this magnet is required to movemember 53, to attracted position as well as to retain it in suchposition. This circuit includes the normally closed contacts i l and 85,so that it is broken if the push button H is not in its normal position,and may be traced as follows: from anode lead ltli to contact 85,contact 84, switch arm 83, lead Hill, through coil 55, lead [Git to theupper terminal of the transformer second ary es; thence through asection of the secondary winding $9 to' dynode ill. Since theelectromagnet 61 is called upon to perform only a holding function, lessthan the maximum current from the tube 8 will sufiice. Accordingly, itmay be connected between the two dynodes 91 and 98. Thus the coil ormagnet 5'5 is interposed in a circuit including dynode 98, dynode 9i,and tap Hi9.

Means are provided for opening the circuit to the transformer primaryHll when the main burner l is extinguished. For this purpose thecontacts 53 and is are interposed in one of the leads as I03 whichsupplies the transformer primary. Thus the transformer 19?]- and tube 8are energized only when armature 65 is in its attracted position.

Further, since the pilot flame 5 is extinguished whenever the mainburner l is extinguished, means are provided for lighting the pilotburner 4 when it is desired to open the control valve 3. For thispurpose, an igniter l is is provided, which may be of any preferredtype, as spark or hot wire, and is arranged to be activated upon openingthe pilot burner valve 1. Thus the igniter Hi] is connected across leads6G2 and "53 by a circuit including the normally open contacts Bi and 82so that the igniter IE9 is operated only when the push button H isdepressed. This cir cuit may be traced as follows: from lead H32, leadIll, igniter H6, lead H2, contact 8|, contact 92, lead H3 to lead I03.

The operation. of the system as a whole will now be discussed. Assumingthat the system is not operatf g, armature 5% will be in its retractedposition indicated by the broken lines and switch contacts 38, i will beopen, pilot burner valve 7 will be closed, member 53 will be in thebroken line position, and the closure !3 of the main valve 3 will be inits closed, broken line position (Fig. 1). Push button ii is nowdepressed to move armature 66 to its attracted full line position. Thisopens the pilot burner valve I, closes contacts T8-19 energizing thephototube 8, closes contacts 8|-B2, energizing the igniter I I0, andopens contacts B4-85. The pilot burner 4 lights very soon thereafter,causing tube 8 to energize the control circuit including theelectromagnet 61 thus maintaining armature 66 in attracted position andholding the pilot burner valve 1 open and contacts 18-49 closed.However, the valve 3 controlling the main burner cannot open due tocontacts B l-85 being separated.

The response of the phototube is practically instantaneous. Hence assoon as the pilot burner 4 lights, the control circuit is energized andpush button ii may be released. It is then returned to its initialposition by spring 12 leaving armature 66 in its attracted position.This opens contacts 81-82 tie-energizing the igniter, and closescontacts til--85 energizing coil 56, which opens the main valve 3 aspreviously explained.

When it is desired to extinguish the main burner I, the entire controlcircuit is de-energized by opening the circuit of the transformerprimary ifll. operating a normally closed push button actuating switchH4.

If the pilot burner 4 fails to light, the phototube 8 cannot energizethe control circuit.

Hence, when push button H is released, arrnature 56 returns to itsretracted position, allowing the pilot burner valve 1 to close andde-energizing phototube 8 by opening contacts 18-49. In view of the factthat the system utilizes an electronic emission device 8 for supplyingcurrent to the manual reset electromagnet 61 and the valve operatingelectromagnet 5d, the automatic process of checking the safety circuitsupon pressing button ll is very rapid. Accordingly, the button need beheld down only for a short period, usually less than a second, and underno circumstances more than two or three seconds. This checking period isconsiderably less than the period of time that the ordinary person wouldbe expected to hold down a button.

The inventor claims:

This may conveniently be done 1. In combination: an electrical energytranslator; means for passing energy to said translator; and a switchcontrolling said translator, comprising: an actuator; means urging theactuator to initial position; a member moved by the actuator; meanscapable of being electrically energized by said translator for holdingsaid member in the position to which it is moved; a first circuitcontroller operated by said member for energizing said energy passingmeans, when the member is in its held position, a circuit derivingenergy from said translator; and a second circuit controller forcontrolling said circuit and operated by return of the actuator to itsinitial position for permitting energization of said circuit.

2. In combination: an electrical energy translator; means for passingenergy to said translator; and a switch controlling said translator,comprising: an actuator; means urging the actuator to initial position;a member moved by the actuator; means capable of being electricallyenergized by said translator for holding said member in the position towhich it is moved; a first circuit controller operated by said memberfor energizing said energy passing means, when the member is in its heldposition, a circuit deriving energy from said translator; means urging.

said member away from its held position; and a second circuit controllerfor controlling said circuit and operated by return of the actuator toits initial position for permitting energization of said circuit.

WILLIAM ALTON RAY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

